Refrigeration



Nov. 19,1929. D. QBJKNIGHT' 1,735,869'

REFRIGERATION Filed Jan. 26, 1927 2 Sheets-Sheet l awuentoz EM 6/ 7 3& AGum (5/07 Nov. 19, 1929; D. B. KNIGHT 1,735,869

REFRIGERATIOIN" I I Fileg Jan. 26, 1927 2 sheets-sham 2 Patented Nov.19, 1929 DONALD B. KNIGHT, F BROOKLYN, NEW YORK REFRIGERATIONApplication filed January 26, 1927. v Serial No. 163,635.

This invention relates generally to the practice of refrigerationthrough the absorp tion of heat in the process of solution of arelatively dry, granular or crystalline substance, such as a salt, in asolvent. In Letters Patent of the United States No. 1,541,968, datedJune 16, 1926, there is described a refrigerating apparatus in whichrefrigeration by the method referred to can be car- 1 ried oncontinuously and automatically, with practically no loss either of thesubstance to'be dissolved or of the solvent and without -manualintervention after the apparatus has been charged with the salt and thesolvent and 'operation' has been initiated. That apparatus, however,designed as described and shown in that patent,,embodied a pump for thedelivery of the solution fromthe tank in which the solution of the saltin the solvent-takes place, with accompanying absorption of heat fromthe refrigerating chamber in which the tank'is' placed, to theevaporator in which the solution is concentrated, the salt and thesolvent being separated and returned separately to the brine tank, wherethe process of solution goes on continuously. In the further developmentof that apparatus and of the process carried on therein, it has beenfound possible, through the application of the present invention, to

dispense with the pump and to produce an apparatus which has no movingparts and in which the process is carried on contmuously andautomatically, with no external means other than a source of heat bywhich the 1 concentration of the solution is accomplished.

and, it may be, a supply of cooling water In the practice of the'present' invention c rculationis dependent mainly upon the dlfl'erencein specific gravity between the solvent and the solution and may bedependent thereon altogether in installations in which the total heightof the apparatus 1s not a controlling factor. In installations 1nWl'llCh height is a controlling factor, an "air lift,

height. In'the apparatus shown in said letting the concentrated solutiontrickle down through a vessel or externally, an agita 56 tube which wascooled tor being provided to bring the saturated solution and the saltas it lost its Water into contact with the cold wall 1 of the tube orvessel, the agitator being another moving part.

In accordance with the present invention the crystallization of the saltis elfected more satisfactorily and economically by permittingthe'solution to p ass in drops or globules through a cooling mediumwhich is immiscible with water, the drops or globules of thehotsaturated solution hardening in their passage into the form of pelletsin readiness for solution in the solvent. The method in which thepresent'invention finds expression or both of, the novel is mainlycharacterized by one or the other features above referred to, while theapparatus in which it also finds expression is characterized by featuresessential to the performance of the method as indicated above and byother features found desirable in the practical application of theinvention.

The invention will be described more fully hereinafter with reference tothe accompanying drawings in which it is illustrated as embodied in asuit which:

Figure 1 is a view partially in elevation able' structure and in andpartially in vertical section, and somewhat diagrammatic, of such anapparatus.

Figure 2 isa detail view in sectional elevation and on a larger scale ofthe upper part of the concentrator.

, Figure 3 is a detail view-in sectional elevation of the dropper at theupper end of the crystallizer and its a ssociated parts.

Figure 4 is aview in sectional elevation-of some of the parts shown inFigure 3, as seen from the right-hand.

Figure 5 is a detail tion on a larger scale the crystallizer.

In describing the i view in sectional elevaof the lower portion ofmprove'd method of refrigeration and the-apparatus in which it iscarried on, it will be convenientto assume that the solution of the saltin the solvent has reached. the boiler or concentrator a which hasassociated with it a source of heat 1) suitablefor evaporation of thesolution. In the embodiment of the invention illustrated, it is assumedthat the height at which the concentrator is to be placed is limited byconsiderations of convenience and the concentrator is therefore shown,as provided with an air or steam lift, which may consist of a tube awith a flaring mouth a at its lower end and extended through and above apartition a near the upper end of the concentrator. Such a lift operatesin usual manner to raise liquid, that is, the concentrated solution,from the lower part of the concentrator to the small chamber a formedabove the partition or diaphragm a Pipe a threaded into the diaphragmw", determines the height at which the concentrated solution may standto the concentrator a through a pipe 0 while the steam is conductedthrough apipe c to a condenser d, which may consist of a coiled pipe (1with an internal pipe d connected to a suitable source ofcooling water.Associated with the condenser is an air-release (1 consisting, it maybe, of a vertical pipe open at its top, for the purpose of releasingnon-condensing gases, or air, and thus preventing-back pressure in thesystem through accumulation of such gases or air.

A pipe e serves to conduct the water of condensation-from the condenserd through a heat exchanger 6 anda pipe 6 to the bottom of thecrystallizer f, which may consist of a vertical vessel, preferablyshaped somewhat as shown, and preferably provided about its upperportion with a cooling shaft f, to which cooling water may be suppliedfrom any suitable source. a

This crystallizer is filled with a cooling medium, such as a mixture ofcarbon tetraher a of the concentrator a is conducted chloride and oil,which is immiscible with water. The recise nature of the cooling mediummay e determined by convenience and the nature of the salt and solventemployed.- It has been found that under the conditions of o rationfollowed hitherto a mixture of car on tetrachloride and oil in suchproportions as to give a specific gravity of about 1.0000, givessatisfactory results.

The hot, saturated solution from the cham- The pipe 9 delivers the hotsolution into a small chamber g from which a determined portion passesthrough a small inner pipe 9 to a dropper at the head of thecrystallizer, the flow of the solution being controlled by a needlevalve 9 The dropper g is formed in any suitable manner to permit dropsor lobules of the hot, saturated solution to pass into the crystallizerin order that each drop or globule may be cooled in its passage throughthe cooling medium in the crystallizer to a temperature to or below thatat which crystallization of the salt will take place. As shown, thedropper consists of-a block g in which is drilled a small duct 9 bywhich the solution is led from the regulating valve 9 to the inside ofthe tubular shield g, seated in a recess formed in the under-side of theblock and provided with a pointed extension 9 In this device-thesolution trickles down on the inside of the-sheet metal shield g andfalls from the point 9 in successive drops which fall through the spaceleft within the glass shield f mounted atthe top of the crystallizer f,into the cooling medium with which the crystallizer is filledpractically to the top.

In order that the circulation of the liquids in the apparatus shall notbe checked by the cooling. of the hot solution between the concentratorand the dropper, and consequent crystallization in the conductor, asurplus of thehot solution is delivered from the concen-- trator throughthe pipe 9 and such surplus is conducted from the chamber g through anexternal pipe 9 which jackets the small pipe g and delivers the hotsolution to the chamber 9 above the dropper, from which chamber thesurplus is conducted through a pipe 9 back' to the concentrator a at apoint be-' low the diaphragm a The volume of the surplus solution thusconducted is suflicient to prevent cooling and crystallization in thesmall pipe 9* and in the dropper g As each drop of the hot concentratedsolution falls from the dropper into the immiscible cooling medium inthe crystallizer, it

quickly solidifiesand descends to the diswhere they are met anddissolved by the already cooled water of condensation, admitted throughthe pipe 6 The cold solution thus formed has ahigher specific gravitythan the cooling medium in the crystallizer and keeps "the coolingmedium somewhat above the bottom ofthe dissolver, as indicated by a lineof separation at f. This line of separation varies more or less underdifferent conditions of operation of the apparatus, but the apparatus isso proportioned that it will stand always above the outlet at 7:.

from which the cold solution is conducted through a suitable coil kwhich is suitably located in the refrigerating chamber indicatedgenerally at 72. .v From the cooling coil it the solution, havingabsorbed heat but still cold, passes through a trap 7L2, which mayconsist of a vertical cylinder in which may be placed a quantity of thecooling medium and in which the cooling medium is displaced I by thecold solution then of greater specific gravity. From the'trap b the coldsolution I passes through apipe 72. the external pipe liquid betweenthebottom of the trap, k

and the. point of return of the solution to the concentrator, if suchvariation should at any time be necessary, there may be interposed inthe pipe k a pressure adjusting device, which is shown as comprising apipe section it", swiveled to the pipeh asv at hi, and communicatingwith a pipe k which is also swivf", between the upper part of thedissolver eled to the pipe h as indicated at h and is provided with ahandle, as at 72.. By'

swinging this adjuster between the horizontal and vertical positions theressure head of'the column of liquid in the pipe 7L between the trap 71.and the highest point of the adjuster can be varied to some extent.

In order that the temperature in the dissolver may be afiected as littleas possible through conduction of heat by the wall of the crystallizer,it is desirable to introduce a heat insulator, as indicated at 7,between the walls of the crystallizer and the dissolver. It is alsodesirable to'provide a connection, as at f and the lower partof thecrystallizr f, to permit the cooling medium to circulate through thecrystals or pellets of salt 1n the upper part of the dissolver, in orderthat the crystals or pellets may be thoroughly cooled before they settleinto the lower part of the dissolver where they come in contact with thesolvent. It is also desirable to provide-a connection f' between the uper part of the trap h -and the lower part 0 the crystallizer in orderto 'permitmovement of the cooling medium between the trap and the lowerpart of the crystallizer accommodate the displacement of the coolingmedium in the trap 0 through variation in the accumu-- lation ofcrystals or pellets in the dissolver.

In the practice of. refrigeration in accordance with the resentinvention, the movements of the hquids, that 1s, of the solution and thesolvent, are due to changes in specific gravities brought about in theThe weights of the columns of balanced and the elevation of whether byoperation. liquid are V the hot, concentrated solution,

vvelevation of the concentrator itself or by the air-lift provided forthe purpose of making unnecessary the elevation of the concentrator, isfor the purpose of maintaining the balance of weights of the columns ofliquid and apparatus.

not for the purpose of creating hydrostatic, head. If absorption of heatin the refrigerat 'ing chamber has proceeded .to the maximum so that theflow of water of condensation through the pipee, the heat exchanger 6'and the pipe 6 into the bottom of the dissolver f is constant; In theevent, thereconcentrated solution through the dropper into thecrystallizer, the accumulation of .3 fore, of any cessation of the flowof the hot,

the crystallized pellets in the lower p'artpf' i the dissolver becomesless through the action of thesolvent matter. As the ,crystalinto thebottom of the dissolver, the displacement of the cooling liquid by thecrystallized pellets in theup er part of the dissolver becomes less andt e line of demarkation, in-

lizedpellets descend out-of the cooling liquid dicated at it in the traph", between the heavier, cold solution which descends to the bottom andthe lighter coo ingmedium which, supplied through the plpej, standsinthe upper part of .the trap, rises somewhat in the trap ht.displacement of the cooling medium in the dissolver is lessened, thecooling medium sinks slightly in the crystallizer, creating a slightnegative pressure in .the air space at the top of the crystallizer, andtherefore pro.- moting the flow of the-hot, concentrated solution fromthe dropper, with-a consequent increase in the quantity ofcr stallizedpellets in the dissolver. On the ot 1er hand, as will be evident,accumulation of the crystallized pellets in the dissolver, displaces thecooling medium, causes it to rise-in the crystallizer, and increases thepressure in the air-space at the top of the crystallizer, therebyretarding the flow of the hot, concentrated solution from the dropper.The trap formed by the pipes g, g, prevents the escape of air fromthe'ainchamber f at the top of the 'crystalliz'er and so prevents theupsetting of the balance and the desirable decrease and increase in theressure in the chamber which contribute to t eautomatic operation of the1 Reference has been made to the balance 'maintained'between the columnsof liquid in the apparatus. This balance is maintained under theoperation of that law of hydrostatics in accordance with which twocolumns Obviously, when the of liquid have the same pressure per s uareinch at their bases when the hi ht one v of the dissolver to theconcentrator. a total height of the crystallizer of thirtycolumnmultiplied by the speci c gravity of the liquid which it contains,equals the height of the other column multiplied b 1 the specificgravity of the liquid in it. Wit

this foundation, the specific gravity of the hot, concentrated solutionbeing known, say at 1.400, and the specific gravity of the solutionreturned to the concentrator being known, say 1.245, with thespeciflcgravity of the cooling medium taken at 1.000, it

' is simply a matter of calculation to determine the height to which thehot, concentrated solution must be raised, "if noair lift is provided,or the height through which it must be raised by the air lift, in orderthat there may" be a balance betweenthe column of hot, concentratedsolution and the column of cold'solution fireturned from the bottori:

six inches from the bottom of the dissolver to the air space at the top,and an air space of three inches, it can be shown that without the airlift the total height from the bottom of the crystallizer and dissolverto the highest pointat which the hot, concentrated solution leaves theconcentrator, -must be about eleven feet.' B employing an air lift, asshown, with a li ting capacity of about four inches, the desired balancecan be secured with a total height of the appartaus of about sevenfeet.-

-' Reference has been made herein to a salt as the material to bedissolved and to water as the solvent, but it will be understood thatthese termsare used as generic terms, the

salt being any solid .or crystalline substance suitable for use and thesolvent being any solvent suitable for use with the selected salt. I

It will be obvious that various modifications can be made in theapparatus to suit different conditions of use and that the invention,therefore, except as pointed out in the accompanying claims,.1s notrestricted .to the particular construction and'arrangetion of a salt ina solvent, which consists in concentrating a salt solution,crystallizing the salt out of the solution, dissolving the salt in thesolvent, returning the solution for concentration, applying heat to thesolution to concentrate the same and passing the hot, concentratedsolution in relatively small portions through a cooling mediumimmiscible withthe solvent to effect cooling ofthe small bod ies ofsolution below the point of crystalliza tion and the hardening of thesame into masses of salt for further solution.

3. A refrigerating apparatus of the character described, comprising arefrigerating device in which the cold solution is received for theabsorption of heat, a concentrator, a crystallizer and dissolver toreceive an im miscible cooling medium and in which the salt iscrystallized out of the solution by reduction in temperature and isreceived in the dissolver for further solution, means includ-- ing adropper to deliver the concentrated,

solution from the concentrator to the crystal lizer in drops, and meansto return thesolu tion from the dissolver to the concentrator,

the crystallizer and dissolver being arranged as a vertically disposedvessel with an air chamber atthe top and a trap being'interposed in theconnection between the concentrator'and the dropper to prevent theescape- 'of air from the'air space. 4. A refrigerating apparatus ofthecharacter described, comprising a refrigerating-=' device in whichthe cold solution is'received for the absorptionof heat, a concentrator,a

crystallizer and dissolver to receive a cooling medium, in w hich refrierating' device the salt is crystallized out o the solution by re-'duction in temperature and is received in the a dissolver'for furthersolution, means to sup-- plysolvent to the dissolver, means to deliverthe concentrated solution from the concentrator to the crystallizer anddissolver, and means to return the solution from the dissolver to theconcentrator, the crystallizer and dissolver being arranged as avertically disposed vessel, and a bv-pass connection being providedbetween the upper part of the dissolver and the lower part of thecrystallizer to permit circulation of the cooling medium.

5. A refrigerating apparatus ofthe character described, comprising arefrigerating device in'which the cold solution is received fortheabsorption of heat, a concentrator, a

crystallizer and dissolver to receive a coolmg medium, 1n whichrefrlgerating device the salt is crystallized out of the solution byreduction in temperatureand is received in thedissolver forfurthersolution, means to supply solvent to the'dissolver, means to de--liver the concentrated solution from the con.-

centrator to the crystallizer and dissolver, andmeans-to-return thesolution from the dissolver to the concentrator, a trap being interposedbetween the refrigerating device and the means to return a solution tothe concen-. trator, and a by-pass connection being provided between theupper part of the trap and i the crystallizer to permit movement of thecooling medium. I I

6. A refrigerating apparatus of the character described, comprising arefrigerating device in which the cold solution is received for theabsorption of heat, a concentrator, a crystallizer and dissolver toreceive a cooling medium, in which refri crating device the saltiscrystallized out 0 the solution by reduction in temperature and isreceived in the dissolver for further solution, means to sup- 7 plysolvent to the dissolver, means to deliver the concentrated solutionfrom the concentrator to the crystallizer and dissolver, and means toreturn the solution from the dissolver to the concentrator, theconcentrator r being .formed as a vertical vessel above a source of heatand with a chamber in its upper end to which is connected the means todeliver the solution to the crystallizer and an i I air lift beingincluded to raise the solution in the concentrator to said chamber.

This specification signed this 20th day of January A. D. 1927.- DONALDB. KNIGHT.

